a. Field of the Invention
The present invention relates generally to buildings which use stacked tongue-and-groove timber construction or the like, in which the lumber is stacked to form the walls of the building, and, more particularly, to a construction for corners of such buildings where the overlapping lumber members of first and second walls come together and are notched to form a corner of the structure.
b. Background
Stacked tongue-and-groove lumber and similar types of construction (e.g., log homes) are commonly used for both recreational structure and homes. In this type of construction, pieces of linear lumber (as used herein, the term "lumber" includes both milled wood and shaved and unshaved logs, as well as similar members formed of plastic or possibly other materials), stacked edge-on-edge to form the wall of the structure. Where two walls come together to form a corner, the overlapping ends of the planks or other pieces of lumber are notched (usually by being cut at the factory, but sometimes on-site) so that these form an interfitting joint structure.
In conventional construction of this type, the corner notches are ordinarily formed by a series of straight-line cuts which extend transverse to the long axis of the lumber member. This traditional form of construction leads to several problems: First, this tends to cause undesirable "light leaks", i.e., small gaps where the outside light is visible from the interior of the structure (or vice-versa). As can be seen in FIG. 3, which is a simplified schematic view of a typical prior art "straight cut" corner joint 01, this is because the structure of the straight-cut notch provides a direct, line-of-sight path 02 by which light is able to enter the interior of the building, through chinks or gaps between the overlying lumber members 04a, 04b, etc. Moreover, this straight-line path provides easy access for cold air and water to also gain entry to the interior of the structure, especially during adverse weather conditions.
Because of these problems, builders of such structures often resort to the expedience of applying calking or other filling material or trim pieces in an attempt to seal the joints. This adds significantly to the cost and difficulty of construction of the structure, often to the point of rendering the structure uneconomical for certain recreational or utility applications. Moreover, the sealant material is subject to deterioration over time, both due to degradation of the material itself and due to shifting of the wooden timbers as they shrink/expand with age and changing weather conditions: as a result, such joints require periodic and expensive maintenance over the life of the structure, yet another disadvantage of such practices is the environmentally suspect nature of the calking/sealant compounds which are commonly used for this purpose.
Yet another problem with conventional, "straight-cut" corner joints is that these ordinarily do not provide a rigid, stable junction, but tend to allow the members to shift back and forth in both longitudinal and lateral directions. This problem results both from the geometry of the "straight-cut" notched joints, and the inability of these joints to compensate for the loose manufacturing tolerances which are a practical necessity when working with wood products. As a result, conventional buildings of this type (unless very small) ordinarily require extensive internal bracing to ensure a rigid structure. The bracing typically takes the form of beams, trusses, or similar supports, and again adds greatly to the cost and complexity of the structure.
Accordingly, there exists a need for a corner structure for use in stacked tongue-and-groove lumber buildings or the like which eliminates any direct, line-of-sight path between the exterior and interior spaces of the building, so as to prevent any light leaks and remove any straight-line paths by which air/water may enter the interior of the building. Furthermore, there exists a need for such a corner structure which is air tight fitting and has a geometry which provides a stable joint despite loose tolerances in the manufacture of the members, so as to provide a rigid structure without requiring extensive internal beams or other bracing. Still further, there exists a need for such a corner joint structure which is economical to produce when using readily available stock lumber as the starting material.